You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
83 lines
1.9 KiB
Go
83 lines
1.9 KiB
Go
package syncx
|
|
|
|
import "sync"
|
|
|
|
type (
|
|
// SharedCalls lets the concurrent calls with the same key to share the call result.
|
|
// For example, A called F, before it's done, B called F. Then B would not execute F,
|
|
// and shared the result returned by F which called by A.
|
|
// The calls with the same key are dependent, concurrent calls share the returned values.
|
|
// A ------->calls F with key<------------------->returns val
|
|
// B --------------------->calls F with key------>returns val
|
|
SharedCalls interface {
|
|
Do(key string, fn func() (interface{}, error)) (interface{}, error)
|
|
DoEx(key string, fn func() (interface{}, error)) (interface{}, bool, error)
|
|
}
|
|
|
|
call struct {
|
|
wg sync.WaitGroup
|
|
val interface{}
|
|
err error
|
|
}
|
|
|
|
sharedGroup struct {
|
|
calls map[string]*call
|
|
lock sync.Mutex
|
|
}
|
|
)
|
|
|
|
func NewSharedCalls() SharedCalls {
|
|
return &sharedGroup{
|
|
calls: make(map[string]*call),
|
|
}
|
|
}
|
|
|
|
func (g *sharedGroup) Do(key string, fn func() (interface{}, error)) (interface{}, error) {
|
|
c, done := g.createCall(key)
|
|
if done {
|
|
return c.val, c.err
|
|
}
|
|
|
|
g.makeCall(c, key, fn)
|
|
return c.val, c.err
|
|
}
|
|
|
|
func (g *sharedGroup) DoEx(key string, fn func() (interface{}, error)) (val interface{}, fresh bool, err error) {
|
|
c, done := g.createCall(key)
|
|
if done {
|
|
return c.val, false, c.err
|
|
}
|
|
|
|
g.makeCall(c, key, fn)
|
|
return c.val, true, c.err
|
|
}
|
|
|
|
func (g *sharedGroup) createCall(key string) (c *call, done bool) {
|
|
g.lock.Lock()
|
|
if c, ok := g.calls[key]; ok {
|
|
g.lock.Unlock()
|
|
c.wg.Wait()
|
|
return c, true
|
|
}
|
|
|
|
c = new(call)
|
|
c.wg.Add(1)
|
|
g.calls[key] = c
|
|
g.lock.Unlock()
|
|
|
|
return c, false
|
|
}
|
|
|
|
func (g *sharedGroup) makeCall(c *call, key string, fn func() (interface{}, error)) {
|
|
defer func() {
|
|
// delete key first, done later. can't reverse the order, because if reverse,
|
|
// another Do call might wg.Wait() without get notified with wg.Done()
|
|
g.lock.Lock()
|
|
delete(g.calls, key)
|
|
g.lock.Unlock()
|
|
c.wg.Done()
|
|
}()
|
|
|
|
c.val, c.err = fn()
|
|
}
|